từ một dung dịch có pH=7 muốn tạo thành dung dịch có pH nhỏ hơn 7 thì cho vào dung dịch
Answer:
you lift my feet off the ground spin me around you make me crazier crazier
Select the container from the figure (Figure 1) that represents the dilution of a 4 % (m/v) KCl solution to each of the following: Figure1 of 1 There is a diagram showing several containers. One container is filled with 4 percent of mass to volume solution of NaCl. Container 1 is filled with a solution in which volume is two times less than the volume of NaCl solution. Container 2 is filled with a solution of a volume two times larger compared to the NaCl solution. Container 3 is filled with a solution of a volume two times larger than the volume of the solution in container 2. Part A 2 % (m/v) KCl
From the dilution formula, we have that at constant value of the solute, the volume of the solution is inversely proportional to the concentration.
The correct responses are;
Part A: Container 2Part B: Container 3Reasons:
The given parameters are;
The concentration of the KCl solution = 4% m/v
Taking the solution as solution of KCl
The volume of the solution in container 1 = Two times less than the volume of KCl solution.
[tex]V_{container \, 1} = \displaystyle \mathbf{ \frac{1}{2} \cdot V_{4\% \, solution}}[/tex]
The volume of the solution in container 2 = Two times larger compared to the volume of KCl solution.
[tex]V_{container \, 2} = \mathbf{\displaystyle 2 \times V_{4\% \, solution}}[/tex]
The volume of the solution in container 3 = Two times larger than the container two solution volume.
[tex]V_{container \, 3} = \displaystyle \mathbf{ 2 \times V_{container \, 2}}[/tex]
Therefore;
[tex]V_{container \, 3} = \displaystyle 2 \times 2 \times V_{4\% \, solution} = \mathbf{4 \times V_{4\% \, solution }}[/tex]
Part A Required:
a. To select the container that represent the dilution of the 4% solution to 2%
Solution:
The dilution formula is; C₁·V₁ = C₂·V₂
Therefore;
[tex]\displaystyle V_1 = \mathbf{\frac{C_1 \cdot V_1}{C_2}}[/tex]
C₁ =4%, C₂ = 2%, we get;
[tex]\displaystyle V_1 = \frac{4 \cdot V_1}{2} = 2 \cdot V_1[/tex]
The volume of the container that represents a 2% dilution is container 2
which is filled with a solution of a volume two times larger compared to the
KCl solution.
Part B:
Required:
The container diluted to a 1% m/v KCl solution.
Solution;
Using the dilution formula, we have;
C₁ = 4%, C₂ = 1%
Therefore;
[tex]\displaystyle V_1 = \frac{C_1 \cdot V_1}{C_2}[/tex]
[tex]\displaystyle V_1 = \frac{4 \cdot V_1}{1} = \mathbf{4 \cdot V_1}[/tex]
The volume of the solution is four times the volume of the 4% KCl solution, which is equivalent to the volume in container 3.
Possible parts of the question are;
Select the container that represents the dilution of the 4% (m/v) KCl solution to obtain the solutions that follows;
Part A: a 2% (m/v) KCl solution
Part B: a solution that is a 1% (m/v) KCl solution
Please see attached drawings
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1. If the wavelength is changed, what will happen to the absorbance values?
Answer:
The longer the path length, the more molecules there are in the path of the beam of radiation, therefore the absorbance goes up. As you likely know from other experiences, a particular chemical species absorbs some wavelengths of radiation and not others
The wavelength is used to determine the concentration of a colored solution since at this wavelength a slight change in concentration allows for a significant change in the absorbance of light.
What is Wavelength?Wavelength is the distance between equal points in adjacent cycles of a wave signal that propagates in space. Each wave has a definite shape and length, so the distance between the peaks is called the wavelength.
It can be calculated by this formula-
[tex]\lambda=\frac{v}{f}[/tex]
[tex]where, \lambda =wavelength\\{v} = velocity\\{f} = frequency[/tex]
Absorbance measures the amount of light with a specific wavelength which a given substance prevents from passing through ii.
Thus, the wavelength is used to determine the concentration of a colored solution since at this wavelength a slight change in concentration allows for a significant change in the absorbance of light.
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PLEASE HELP ME ASAP
Use the equation to answer the question.
4NaCl + 2502 +_____
H2O +______02 →______Na2SO4 + 4HCI
Which numbers balance this equation?
(1 point)
O 2, 1, 2
O 1,2,4
O 2, 1,4
o 1,2,2
Answer: O 2, 1,4
Explanation:
The sum of the number of proteins and neutrons in an atoms nucleus is its __________ ___________.
Answer:
Mass Number
Explanation:
In nuclear physics, the sum of the numbers of protons and neutrons present in the nucleus of an atom.
Please vote brainliest!
Using the combined gas
law, what is the final
volume of the Helium gas?
This is the answer i hope it helps
A sample of gas has Pi = 0.768 ATM, Vi = 10.5 L, and Ti = 300 K. What is the final pressure if VF = 7.85 L and T and f = 250 K?
Hot air balloons are open at their lower and end. A basket is suspended from the balloon and can take several passengers as well as the pilot. A propane burner fixed to the basket is used to heat up the air in the balloon A hot balloon has a volume of 1500 m3 and its volume does not change when the enclosed air is heated.
1) Use the ideal gas equation, pV=nRT. to calculate how many molecules of the balloon contains at a temperature of 10 °C and a pressure 10.1 KP.
2) Calculate the mass of air it contains, assuming an average M of 29.
(a) The number of molecules contained by the balloon at the given condition is 6,438.97 moles.
(b) The mass of air in the balloon is 186.73 kg.
The given parameters;
volume of the balloon, V = 1500 m³temperature, T = 10⁰C = 273 + 10 = 283 Kpressure, = P = 10.1 kPa = 10,100 PaThe number of molecules contained by the balloon at the given condition is calculated as follows;
[tex]PV = nRT[/tex]
where;
R is ideal gas constant = 8.314 J/mol.Kn is the number of moles air in the balloon;[tex]n = \frac{PV}{RT} \\\\n = \frac{10,100 \times 1500}{8.314 \times 283} \\\\n = 6,438.97 \ moles[/tex]
The mass of air in the balloon is calculated as;
[tex]n = \frac{m}{M} \\\\m = nM\\\\m = 6,438.97\ moles \ \times \ 29 \ g/mol\\\\m = 186.73 \ kg[/tex]
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How many grams are 0.300 moles of glucose, C6H12O6?
Answer:
Explanation:
Firstly, let us calculate the molar mass of the glucose. To find the molar mass we need to add the masses of individual elements which constitute one glucose molecule.
Now, we know that
Molar mass of Carbon C=12gmol−1
Molar mass of Hydrogen H=1gmol−1
Molar mass of oxygen O=16gmol−1
Therefore, Molar Mass of glucose (C6H12O6) can be calculated as shown below
⇒ 6×12+12×1+6×16
⇒72+12+96⇒180gmol−1
Given mass of glucose = 300g
Now, we can calculate the number of moles in given mass of glucose, using the below formula,
Using the Formula numberofmoles=givenmassmolarmass we get
numberofmoles=300180 = 1.7 moles or 2 moles (approx.)
Hence the number of moles present in 300 g of glucose is 1.7 moles or 2 moles approximately.
What are the dependent and independent variables in this experiment? How are outside factors being controlled in this experiment to make sure that the results test only the dependent variable?
Answer:
1. An independent variable is manipulated, or changed. The dependent, or responding variable, changes based on the independent variable. The dependent variable is examined.
2. It is a controlled experiment.
Explanation:
In a controlled experiment all variables are kept the same, except for the one being tested, which is called the experimental variable , or independent variable . This group is the experimental group . The group that is not affected by the experimental variable is the control group .
Very often a graph will be used to analyze the results of the experiment. The independent/experimental variable is placed on the x-axis and the dependent variable is placed on the y-axis. The dependent variable is what is measured as a result of the application of the experimental variable.
A variable that is independent is altered. Based on the independent variable, the responding variable, or dependent variable, alters. Examining the dependent variable. The experiment is carefully controlled.
What is an independent variable ?In mathematical modeling, statistical modeling, and experimental sciences, there are dependent and independent variables. Dependent variables get their name because, during an experiment, their values are investigated under the presumption or requirement that they are dependent on the values of other variables due to some law or rule.
A variable that is independent is precisely what it sounds like. It is a stand-alone variable that is unaffected by the other variables you are attempting to assess. Age, for instance, could be an independent variable.
When doing an experiment, the independent variable is what you alter, and the dependent variable is what changes as a result of that change. This is an easy way to conceive of independent and dependent variables.
Thus, based on the independent variable, the responding variable, or dependent variable, alters.
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A student mixes some soap with water and then blows through a straw into the solution. Bubbles form. Do you think a chemical change has taken place? Explain
Answer:
No it has not.
Explanation:
The actual chemical compound has not changed, the materials have mixed but no reaction has taken place. Blowing the bubbles causes a physical change. Hope this helped!
Mixing soap and water and forming bubbles is a physical change as there is no change in composition.
What is a physical change?
Physical changes are defined as changes which affect only the form of a substance but not it's chemical composition. They are used to separate mixtures in to chemical components but cannot be used to separate compounds to simpler compounds.
Physical changes are always reversible using physical means and involve a change in the physical properties.Examples of physical changes include melting,boiling , change in texture, size,color,volume and density.Magnetism, crystallization, formation of alloys are all reversible and hence physical changes.
They involve only rearrangement of atoms and are often characterized to be changes which are reversible.
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Environmental scientists collect air samples so they can test the quality of the air. They start with rigid metal containers that are completely empty—the air has been pumped out of them.
What happens to the pressure inside the container and the volume of the container as air enters it?
Explanation:
filling air inside an empty o2 medal containers, if air is added, the air inside, creates volume inside.
due to heat, weather,... depending on what indoor or outdoor storage said containers r placed in,;
So, I can't give you an answer, due to lack of details..sorry...
Ionic compounds in own words
an ionic compound is made of two or more elements held by a strong electrostatic force. metal atoms lose electrons to become positive ions, and non metals gain electrons to become negative ions. ionic bonding occurs between metals and non metals
In experiment 9, in one operation, we heat up the alcohol with acid and do a concurrent distillation. What was the purpose of doing this
Answer:
we heat up because the component with lower boiling evaporates first,
leaving the other behind
*1. The internal energy with a system associated with the motion of particles and that can be added to a substance is called_____.
A. Thermal energy
B. Electrostatic forces
C. Temperature
D. Kinetic energy
•
•
•
*2. Which statement describes the effect of adding more energy to a system, assuming a phase change does not occur?
A. The particles within the system will have greater motion, and the temperature will decrease.
B. The particles within the system will have greater motion, and the temperature will increase.
C. The particles within the system will have less motion, and the temperature will increase.
D. The particles within the system will have less motion, and the temperature will decrease.
•
•
•
*3. Which statement correctly describes how attractions that hold particles break?
A. Attractions due to electrostatic forces. When particles have low enough energy, these forces can no longer keep particles together.
B. Attractions due to gravitational forces. When particles have low enough energy, these forces can no longer keep particles together.
C. Attractions due to gravitational forces. When particles move fast enough, these forces can no longer keep particles together.
D. Attractions due to electrostatic forces. When particles move fast enough, these forces can no longer keep particles together.
•
•
•
*4. Which statement explains why a rubber band analogy is not a perfect comparison for bonds in a substance when considering phase changes?
A. For a phase change from liquid to gas, the bonds break completely and particles can move independently of each other.
B. For a phase change from liquid to gas, the bonds do not break completely and the particles can still slide past each other.
C. For a phase change from solid to liquid, the bonds break completely and particles can move independently of each other.
D. For a phase change from solid to liquid, the bonds do not break completely in the particles can still slide past each other.
•
•
•
*5. The boiling point of benzene is 80°C. Which pair of samples will have the same average kinetic energy as benzene molecules?
A. Two samples of liquid benzene, one at 70°C in the other at 80°C.
B. A sample of liquid benzene at 70°C and a sample of gaseous benzene at 90°C.
C. Two samples of gaseous benzene, one at 80°C in the other at 90°C.
D. A sample of liquid benzene at 80°C and a sample of gaseous benzene at 80°C.
Answer:
1. A/Thermal Energy
2. B/The particles within the system will have greater motion, and the temperature will increase.
3. C/Attractions occur due to electrostatic forces. When particles move fast enough, these forces can no longer keep particles together.
4. D/ For a phase change from solid to liquid, the bonds do not break completely and particles can still slide past each other.
5. D/ a sample of liquid benzene at 80ºC and a sample of gaseous benzene at 80ºC
Explanation:
I took the Test.
1. Internal energy associated with systems and particles is thermal energy. Thus, option A is correct.
The internal energy has been described as the energy that has been assessed by the molecules and bonds at the STP. Thermal energy has been the energy of particular molecules and the system comprising all the molecules have the summation of the thermal energy.
Thus, internal energy associated with systems and particles is thermal energy. Thus, option A is correct.
2. The addition of energy results in greater motion with an increase in temperature has been representation no phase change. Thus, option B is correct.
The addition of energy to the substance results in the increased motion of the particles. The energy higher than the threshold energy has been responsible for the phase change of the substance.
The addition of energy results in greater motion with an increase in temperature has been representation no phase change. Thus, option B is correct.
3. The movement of the particles under the gravitational attraction is not enough to hold the particles together at a longer distance. Thus, option B is correct.
The attraction has been the force that has been responsible for holding the particles in a molecule. Different attractions have a different levels of stability and strength.
The movement of the particles under the gravitational attraction is not enough to hold the particles together at a longer distance. Thus, option B is correct.
4. The phase change of the molecules has been mediated by overcoming the force of attraction that allows the molecules to move freely. The solid to liquid phase change has been mediated with the breaking of the attraction between the bonds allowing free movement.
Thus, statement 4 is incorrect, and option D is correct.
5. The kinetic energy has been the energy possessed by the moving molecules in the medium. The molecules in liquid and gas have been possessing the same energy at the same temperature, Thus, option D is correct.
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HELP ME OUT PLEASE!!
Which model represents the chemical formula NO2, nitrogen dioxide?
A) A.
B) B.
C) C.
D) D.
Answer:
C
Explanation:
The answer is C, because nitrogen is in purple, and oxygen is in blue, and in NO2 you have 2 oxygen atoms.
Cesium-137 is part of the nuclear waste produced by uranium-235 fission. The half-life of cesium-137 is 30.2 years. How much time is required for the activity of a sample of cesium-137 to fall to 8.32 percent of its original value
Answer:
la primera va con la última
1 ton of methanol are accidentally discharged into a lake. By how much is the biological oxygen demand of this water increased
The biological Oxygen demand of the lake is increased by 1.5 ton.
Discussion:
The reaction of methanol with Oxygen is as follows;
2CH3OH + 3O2 ==> 2CO2 + 4H2O.In the reaction above; Since Methanol, CH3OH and Oxygen, O2 have the same molar mass; 32.
Therefore we can say since;
2 moles of CH3OH requires 3 moles of O2.
Therefore, 1 ton of methanol will require 1.5 ton of oxygen.
The biological Oxygen demand of the water is therefore increased by 1.5 ton as this is the amount of Oxygen consumed by the ethanol.
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radium-223 decays with a half-life of 11.4 days, how long will it take for a 0.240-mol sample of radiuim to decay to 1.88 x 10-3 mol
The time taken for 0.240 mole sample of radiuim to decay to 1.88×10¯³ mole is 79.8 days
We'll begin by calculating the number of half-lives that has elapsed.
Original amount (N₀) = 0.240 mole
Amount remaining (N) = 1.88×10¯³ mole
Number of half-lives (n) =?N = 1/2ⁿ × N₀
1.88×10¯³ = 1/2ⁿ × 0.240
Cross multiply
1.88×10¯³ × 2ⁿ = 0.240
Divide both side by 1.88×10¯³
2ⁿ = 0.240 / 1.88×10¯³
2ⁿ = 128
2ⁿ = 2⁷
n = 7Thus, 7 half-lives has elapsed
Finally, we shall determine the time.Number of half-lives (n) = 7
Half-life (t½) = 11.4 days
Time (t) =?t = n × t½
t = 7 × 11.4
t = 79.8 daysTherefore, the time taken for 0.240 mole sample of radiuim to decay to 1.88×10¯³ mole is 79.8 days
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Which statement best describes mechanical energy?
A.the energy of heat and magnetism
B.the energy of electricity and motion
C.the energy of moving parts and motion
D.the energy of electricity and heat
Answer:
the answer is B.
Explanation:
your welcome
Answer:
the answer is B
Explanation:
i have the same exact questionn
Electromagnetic waves travel fastest through
A -Solid
B -Liquid
C -Gas
D-Vacuum
Answer:
Gas
Explanation:
Mechanical waves- travel faster in solids & slowest in gases
Electromagnetic waves- travel fastest in empty space and slowest in solids.
Because they are so close, than can collide very quickly, i.e. it takes less time for a molecule of the solid to 'bump' into its neighborough. Solids are packed together tighter than liquids and gases, hence sound travels fastest in solids. The distances in liquids are shorter than in gases, but longer than in solids.
Answer C- Gas
Explanation:
Electromagnetic waves- travel fastest in empty space and slowest in solids.
The mass of a metal ball was 20.350 g. The volume of the water in a 25 mL graduated cylinder was increased from 16.05 to 17.90 mL when the metal ball was placed in the cylinder. What is the density of the metal ball
Answer:
11000 g/L
Explanation:
Since density is mass divided by volume, find the volume of the metal ball by subtracting the initial volume of water in the graduated cylinder from the ending volume. In this case, the volume would be 17.90 mL - 16.05 mL = 1.85 mL = 0.00185 L. Then using the formula for density, calculate 20.350 g / 0.00185 L = 11000 g/L.
Density is an intensive property as it does not depend on the quantity of the substances Whereas mass and volume are extensive property. Therefore, the density of the metal ball is 11000 g/L.
What is density?Density tells about the compactness of the substances, how much dense is the substances in other words. Object that is more denser than water they just sink in the water.
Mathematically,
Density = Mass of the metal ball ÷volume marked on the graduated cylinder
volume=ending volume- initial volume of water in the graduated cylinder
=17.90 mL - 16.05 mL
= 1.85 mL
= 0.00185 L.
substituting all the given values in the above equation, we get
density= 20.350 g / 0.00185 L
= 11000 g/L.
Therefore, the density of the metal ball is 11000 g/L.
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Which stage of a fire can be described as follows: The flames are not visible and the combustible item no longer generates heat or combustion products
Fire extinguishment is referred to the stage in which flames are not visible
and the combustible item no longer generates heat.
This stage refers to when the fire has been put out through a fire
extinguisher or other compounds. When fire is put out, there is no longer
flames present.
The absence of flames also means that there is no heat generation or
combustion products due to the absence of a heat source.
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A mixture of methanol and water was distilled using both simple distillation and fractional distillation. Which statement is NOT true
With regard to distilling the mixture of methanol and water using simple
distillation and fractional distillation, a statement that can be made that is
not true is that; Methanol and water form an azeotrope.
Reasons:
Azeotrope are liquid mixtures that have the property of a constant boiling
point due to the contents of the vapor are the same as the mixture.
Water when mixed with methanol form network structures. However,
methanol does not form a binary azeotrope with water.
Therefore, a statement that is not true is that methanol and water form an
azeotrope a mixture that has a constant boiling temperature.
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Question 2
Which of the following models the arrangement of atoms in a gas?
O None of these
PLEASE HELP ASAP
Answer:
The option where the atoms are furthest apart.
Explanation:
Gasses are the most energetic of the three basic states of matter, their atoms have more kinetic energy than either solids or liquids and will therefore also have the most spread out atoms.
chlorine has two isotopes chlorine-35 and chlorine-37 with average atomic mass 35.5.find the percentage abundance of each isotopes
Answer:
75% Cl-35 and 25% Cl-37
Explanation:
chlorine has two isotopes chlorine-35 and chlorine-37 with average atomic mass 35.5.find the percentage abundance of each isotopes
assume Cl-35 has Y% Then Cl-37 has (100-Y) %
The weighted average of 35.5 is given by
[(35 x Y) + ((100-Y) x 37)]/100 = 35.5
so
(35 x Y) + ((100-Y) x 37) =3550
35Y + 3700 -37Y = 3550
-2Y = -15075% Cl-35 and 25% Cl-37
Y = so average weight chlorine is
75% Cl-35 and 25% Cl-37
HELP ME OUT PLEASE!!
Barium sulfate, BaSO4 is a white crystalline solid that is insoluble in water. It is used by doctors to diagnose problems with the digestive system,
Barium hydroxide, Ba(OH)2 is also a white crystalline solid and is used in wastewater treatment.
How many more oxygen atoms are represented in the formula for barium sulfate than in the formula for barium hydroxide?
A) 2
B) 4
C) 1
D) 8
Answer: 2
Explanation:
Ba(OH)2 contains two oxygen atoms
BaSO4 contains four oxygen atoms.
This means that barium sulfate contains two more oxygen atoms than barium hydroxide in its formula.
Hope this helps!! :)
According to formula BaSO₄, Barium sulfate contains 2 more oxygen atom.
The correct option is (A) 2
Barium sulfate's distinguishing featureBa(OH)₂ has two oxygen atoms in it.
Four oxygen atoms may be found in BaSO₄.
This indicates that the formula of barium sulfate has two extra oxygen atoms than the formula of barium hydroxide.
Barium sulfate, often known as BaSO4, is a transparent white pigment that has a long history. It is produced by combining sulfuric acid with barium hydroxide and other sources of barium.
Chemically speaking, barium hydroxide has the formula Ba(OH)2. The monohydrate of barium, sometimes referred to as baryta or baryta-water, is one of the element's main compounds. The typical commercial form of monohydrate is this white granular substance.
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which mass movement does this describe?
Answer:
landslide mudflows slump and creep
Explanation:
no explanation
the bleaching action of sulphur (iv) oxide is by
Answer:
The bleaching action of sulphur di oxide is temporary because it involves the process of reduction. sulphur di oxide removes oxygen from the coloured substance and makes it colourless. Atmospheric oxygen slowly takes place of the removed oxygen and because of which the material regains the co
A mixture of 3.25 moles of oxygen gas and 2.75 moles of nitrogen gas exert a total pressure of 22.4 atm. What is the partial pressure of oxygen
The partial pressure of oxygen is equal to 10.2 atm.
Given the following data:
Number of moles of oxygen = 3.25 moles.Number of moles of nitrogen = 2.75 moles.Total pressure = 22.4 atm.To determine the partial pressure of oxygen:
First of all, we would find the total number of moles of the elements:
[tex]n=3.25+2.75[/tex]
n = 6 moles
Next, we would determine the mole fraction of the oxygen by using this formula:
[tex]Molefraction \;of \;a \;substance =\frac{No.\; of \; moles \;of \;substance}{Total \;no. \;of \; moles \;of \;substances}[/tex]
Substituting the values, we have:
[tex]Molefraction \;of \;a \;substance =\frac{2.75}{6} \\\\Molefraction \;of \;a \;substance =0.4583[/tex]
For oxygen:
[tex]Partial \;pressure = Molefraction \times Total\;pressure\\\\Partial \;pressure = 0.4583 \times 22.4[/tex]
Partial pressure of oxygen = 10.2 atm.
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Answer:
12.1
Explanation:
3.25 + 2.75= 6 moles total
then take: 3.25/6 to get 0.542
multiply 0.542 by 22.4 to get 12.1
the other answer solved for nitrogen, not oxygen.
What is your opinion of Latino immigrants in your country?
Answer:
I believe they deserve to be here.
Explanation: